As shown in FIG. 1, an existing laser transmitter includes a fiber adapter 101, a cavity 102, and pins 103 and 104. Electronic devices of the laser transmitter include a laser and other electric device located in the cavity; light emitted by the laser enters a fiber by using the fiber adapter; the pins 103 and 104 are welded on opposite surfaces of a same ceramic substrate; and the pins supply power for the laser and the other electric device by means of connection to an external circuit.
As shown in FIG. 2, an interior of the cavity includes a heat sink 201, a laser 204, and ceramic substrates 202 and 203. A surface of the heat sink 201 is pasted with a conducting layer, and a cathode of the laser 204 is laminated to the conducting layer; a surface of the laser 204 has an anode welding point 206, and a conducting strip insulted with the conducting layer is disposed between the laser and the other end of the heat sink; a surface of the ceramic substrate 202 has a conductor 205A; the conductor 205A is welded with the pin 103; a surface of the ceramic substrate 203 has a conductor 205C; and the conducting layer is located in a same horizontal plane as the surface of the ceramic substrate 203 having the conductor 205C.
As shown in FIG. 3, FIG. 4, and FIG. 5, a conductor 205B on a surface of the ceramic substrate 202 is welded with the pin 104; the pin 103 and the pin 104 are welded on opposite surfaces of the ceramic substrate 202; the surface of the ceramic substrate 203 has the conductor 205C; and the surface having the conductor 205B is laminated to the surface having the conductor 205C, so that conductors 205B and 205C on two surfaces abut. However, high-speed signal transmission demands that the laser transmitter meets an impedance matching requirement needed by a high frequency signal. Impedance matching, as a part of microwave electronics, is mainly used for a transmission line, so as to achieve an objective that all high frequency microwave signals can be transmitted to a point of load and no signal is transmitted back to a source point, thereby improving quality of the high frequency signal.
As shown in FIG. 5, owing to a narrow conductor and a limited manufacturing technology, this transit connection manner makes the conductors 205B and 205C staggered during abutting, which causes a large error. Existence of the error destroys impedance matching preset for the high frequency signal, so that the high frequency signal provided by means of the conductor 205C, the conductor 205B, and the pin 104 for the laser 204 does not satisfy the impedance matching requirement.
As shown in FIG. 2, if the high frequency signal is provided for the laser 204 by means of the conductor 205A, the conductor 205C, the conductor 205B, and the pin 104 supply power for the other electric device. In order to connect the other electric device to the conductor 205C, a gap needs to be set on the ceramic substrate 202. When the cathode of the laser 204 is connected to the conductor 205A by means of a gold wire through the conducting layer, the anode welding point, and the conducting strip, owing to existence of the gap and that the conducting layer and the conducting strip, and the conductor 205A are located in two planes with two different heights, causing a large distance between the conducting layer and the conducting strip, and the conductor 205A, and a needed gold wire of a long length, so that the high frequency signal provided by means of the conductor 205A for the laser 204 does not satisfy the impedance matching requirement.